PHILADELPHIA (CBS) — A demonstration by immigration advocates shut down roads in Center City. This demonstration gave the Philadelphia Police department a chance to run through its protest protocols ahead of the Democratic National Convention next month.

Organized by Juntos, the rally began at the ICE office at 16th and Spring Garden. The group then moved to the off ramp of the Vine Expressway on Broad Street.

Four protesters, including a 13-year-old boy who’s mother would have been protested under President Obama’s immigration orders before the Supreme Court ruling last week, used arm locks to chain themselves together to shut down the expressway exit.